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Date and Time of the Query: 2019-06-17 T03:12:49 PDT
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For refcode 1996MNRAS.278..841d:
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Copyright by Royal Astronomical Society. 1996MNRAS.278..841d Metallicity and abundance ratios in elliptical galaxies J. A. de Freitas Pacheco Observatoire de La Cote d'Azur Departement A. Fresnel, Boite Postale 229, Nice 66364, Cedex 4, France Accepted 1995 September 4. Received 1995 July 24; in original form 1995 January 23 ABSTRACT Using the theoretical results of Barbuy, the variation of the Mg_2_ index as a function of the stellar parameters (T_eff_, log g, [Fe/H]), including the Mg/Fe ratio, is obtained. This allows a new calibration of the metallicity indicators Mg_2_ and <Fe> through synthetic indices computed for stellar populations having a metallicity spread and ages of the order of 14-16 Gyr. The models indicate that the integrated Mg_2_ index depends on the chemical history, since it varies not only with the metallicity but also with the average Mg/Fe ratio. The study of a sample of elliptical galaxies shows that on average, [Mg/Fe]^bar^ = 0.40, comparable to the values observed in metal-poor galactic halo stars. This confirms the early suspicions that elliptical galaxies (Es) had a very high star formation rate in the past, ad that the enrichment was caused by massive stars. Key words: galaxies: abundances - galaxies: elliptical ad lenticular, cD - galaxies: evolution.
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